Piles are used in a number of applications including, for example, supports for structures, such as decks and marine docks, and anchors to which separate structures are attached, for example by means of cables. Typically, a lower portion of a pile is driven into a displaceable or penetrable material, such as earth, soil or sand. An upper portion of the pile extends outward from the material into which the lower portion has been driven, and is typically attached to a separate structure, such as a deck, or provides an anchoring point.
Typically, piles must be sufficiently robust so as to both withstand insertion into a displaceable material, and provide support for structures that may be subsequently attached thereto. Insertion into the displaceable material (e.g., soil) is often achieved by driving (e.g., pounding) the pile directly into the displaceable material. As such, piles are often fabricated from wood and/or metal, for example, in the form of solid rectangular beams or I-beams. Wood and metal beams, while sufficiently robust, are subject to rot and corrosion in many environments in which they are used. In addition, wood and metal beams can be heavy, resulting in increased fuel costs associated with transporting to and handling thereof at the work site.
Piles may also be formed in-situ. For example, a cylinder is inserted into the ground with the concurrent supply of a high pressure fluid, such as water, and concrete is then pumped into and optionally around the inserted cylinder. See, for example, U.S. Pat. Nos. 3,354,657; 3,636,718; 3,664,139; and 3,842,608.
In addition to being sufficiently robust so as to both withstand insertion into the ground, and provide load bearing support, it is also desirable that the pile be sufficiently retained within the ground. Retention of the pile within the ground may be achieved by pumping concrete around the base and/or the sides of the lower portion of the pile. Alternatively, or in addition thereto, the lower portion of the pile may be fitted with screw-like lateral extensions that serve to hold the pile within the ground.
It would be desirable to develop new pile designs that provide a combination of light weight and high strength. In addition, it would be further desirable that such new pile designs also provide for improved retention of the pile within the material into which it is driven.
U.S. Pat. No. 844,294 discloses an anchor that includes: an end-section having a plurality of barb-shaped enlargements; at least one superposed section that is connected to the end-section; and at least one pipe extending the length of the anchor, for passage of water there-through during sinking of the anchor into the ground. The anchor of the '294 Patent is fabricated from molded plastic.